Quick sort of basic algorithm series

Quick sort, like bubble sort, is also a kind of exchange sort.
The criterion of quick sort is "find the base number, separate the size; divide and conquer, recursive use". The basic code is as follows:

public static void quickSort(int[]arr,int start,int end){
    
    
	if(start < end){
    
    
		int stard = arr[start];		//找到基准数
		int low = start;		//定义排序下标和上标
		int high = end;
		while(low < high){
    
    
			while(low < high && stard <= arr[high]){
    
    
   				high--;
 			 }
 			 arr[low] = arr[high];
 			while(low < high && stard >= arr[low]){
    
    
     				low++;
  			 }
   			 arr[high] = arr[low];
   		}
   		arr[low] = stard;		//第一轮排序结束
   		quickSort(arr,start,low);	//递归调用
   		quickSort(arr,low+1,end);
	}
}